In a wavelength division multiplexed (WDM) network, optical signals may be switched from one optical communication link to another. In order to achieve such switching, the optical signals are often received from a first optical link at a node and converted to electrical signals. The electrical signals are then used to generate further optical signals, which are supplied to a second optical link connected to the node.
An alternative approach involves all-optical switching, whereby optical signals are received from one or more links at a node, and directed to corresponding output links at the node without optical-to-electrical conversion. Because there is no optical-to-electrical conversion at the node, it may be difficult to convert a signal on a circuit to a different wavelength at the node. Accordingly, a circuit must have the same wavelength assigned along each link in its path. In addition, any circuits traversing a particular link in the network must each be assigned a different wavelength. Moreover, wavelength availability may depend on factors other than the above-noted constraints. For example, certain transmitters may be less expensive than others.
Accordingly, there is a need for an optimal wavelength assignment method that takes into account multiple parameters.